1. Field of the Invention
The present invention relates to a wired circuit board holding sheet and to a production method thereof. More particularly, the present invention relates to a wired circuit board holding sheet which is in the form of a sheet in which a plurality of separable wired circuit boards are held and to a production method thereof.
2. Description of the Prior Art
A wired circuit board is usually produced in the manner that a plurality of wired circuit boards are formed in a single sheet and, then, are separated off after electronic components are mounted on the respective wired circuit boards.
In this wired circuit board holding sheet which is in the form of a sheet in which a plurality of separable wired circuit boards are held, the respective wired circuit boards are held in the sheet via joints. It is usual that the joints are indented from the both front and back sides thereof by punching to make V-shaped cutting notches so that the joints can be cut easily by folding.
However, when the cutting notches are formed by punching, variations in depths of the notches may result easily. If a cutting notch has an insufficient depth, the joint cannot be cut smoothly by folding. If the joint is tried to be cut by folding it forcibly, then a wired circuit board and an electronic component mounted thereon may be damaged.
For example, JP Laid-open (Unexamined) Patent Publication No. 2000-323812 proposes the method that the presence of break in the form of V-shaped cutting notches, along which the sheet is split into a plurality of wired circuit boards, is electrically detected to prevent incorrect mounting of the electric and electronic circuit components, so as to ensure the mounting of electric and electronic circuit components on their respective wired circuit boards.
However, the method of JP Laid-open (Unexamined) Patent Publication No. 2000-323812 of electrically detecting the presence of break in the form of a V-shaped cutting notch requires a conductive testing device, involving the disadvantages of cost increase and troublesome work for such a conduction test.
In addition, although the method of JP Laid-open (Unexamined) Patent Publication No. 2000-323812 can permit the detection of the presence of a V-shaped cutting notch, it cannot permit the judgment on whether the cutting notch has a predetermined depth. Due to this, this method still cannot solve the problems mentioned above, namely, the problem that if the cutting notch has an insufficient depth, the joint cannot be cut smoothly by folding and the problem that if the joint is tried to be cut by folding it forcibly, then a wired circuit board and an electronic component mounted thereon may be damaged.